//这是做适配的 用rem来写的
@media screen and (min-width: 320px) {
    html {
      font-size: 16px;
    }
  }
  @media screen and (min-width: 360px) {
    html {
      font-size: 18px;
    }
  }
  @media screen and (min-width: 375px) {
    html {
      font-size: 18.75px;
    }
  }
  @media screen and (min-width: 380px) {
    html {
      font-size: 19px;
    }
  }
  @media screen and (min-width: 414px) {
    html {
      font-size: 20.7px;
    }
  }
  